Here's why:

* Electronic Configuration: Boron has an electronic configuration of 2s² 2p¹. It has three valence electrons in its outermost shell.

* Octet Rule: Boron wants to achieve a stable octet configuration, meaning it needs eight electrons in its outermost shell.

* Covalent Bonding: Boron achieves this stability by sharing its three valence electrons with other atoms, forming three covalent bonds.

Example: In boron trifluoride (BF3), boron forms three covalent bonds with three fluorine atoms.